


A Lesson in Biology

by Ballycastle_Bat



Category: The Flash (TV 2014)
Genre: Alternate Universe - Soulmates, Angst, F/M, First work in this trope, Hanahaki Disease, Mutual Pining, Not Actually Unrequited Love, Platonic Soulmates, Romantic Soulmates, Teenagers, Unrequited Love, Wizards of Waverly Place Reference, hanahaki disease au
Language: English
Status: Completed
Published: 2018-07-21
Updated: 2018-07-24
Packaged: 2019-06-12 22:15:53
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 2,980
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15349911
Author URL: https://archiveofourown.org/users/Ballycastle_Bat/pseuds/Ballycastle_Bat
Summary: Iris still didn't understand soulmates, platonic ones, romantic ones ... it was too much science and biology for her. She didn't understand Hanahaki disease either, not realy. So Barry explains.





	1. Chapter 1

**Author's Note:**

> So I've always wanted to try out this trope out and WestAllen is kind of my default the's days? I'll definitely try to put my own spin on it as much as I can, but you can find info on the original trope here: https://fanlore.org/wiki/Hanahaki_Disease
> 
> I think I'll write a longer/better fanfic for them with the trope in the future, and an OliBarry too kost likey.

**Central City 2005**

Sixteen year old Barry Allen was clumsy and awkward with long thin limbs that hadn't learned how to corporate well yet. It was who he was. He was almost the exact opposite of Iris’s type, she mused as she sat across from him at the kitchen table. She liked her men rugged, and chiseled, like her friend Tiffany’s cousin Hal who she’d been lusting after since that pool party last year. So why on _earth_ was she completely in love with Barry Allen? Not that she would ever admit that to herself.

What she was worried about right now, was _soulmates_. Finding another person to keep you alive? That was stressful. The pair had just completed a brief course in Health Class that was equal parts vague and concerning. They made it sound like the end of the world if you didn't have one. This after the sex ed course was almost enough to make Iris swear off men.

“Why are you staring at me like that?” Barry reached across the table to grab the maple syrup. “You feeling okay?” he poured a generous amount onto his pancakes before pushing the bottle down her way. It was early on a Tuesday morning at the West house.

“Huh? Sorry I was just thinking. I don't think I realised where I was looking.” she looked down at her plate.

“Are you nervous because of that soulmate thing we talked about in health class?” stuffed a bit of pancake into his mouth.

“A little.” she confessed softly, leaning on her hand, ignoring her breakfast.

“You know, I've studied the science behind Soulmates well beyond what the told us in Health Class.” he informed her, scratching at his arm a little with the end of the fork he didn't put in his mouth. “They aren't always romantic, for one. For example, Jeremy from science could be my Soulmate and trust me, Jeremy is not my type. A lot of people just fall in love with their Soulmates so it's become an assumption that you're meant to be with them.” he began, eating another bit of pancake.

“Really?” Iris leaned closer, actually thankful for his nerd rant this time.

“It's just sort of a _thing_ …” he shrugged. “It's someone who's cellular structure responds to yours. Being with them gives you a longer, healthier life because your immune systems kinda link up.” he took another bite of his pancakes. “It's really easy for people to romanticise stuff like that ... I know how serious you are about choosing your own path in life and your free will. You still have that. Soulmates are optional and can be best friends.” he explained further, hoping he made sense and wasn't talking in circles. “You really only need to worry if you’re sick like me and don't get along with your soulmate. There's a bunch of science behind it but I know that would stress you out more so I'm keeping it simple.” he reached over and gave her hand a little squeeze. “People act like you have to run off and marry your soul mate and have six kids or you'll die, or it forces you to love someone. When that's actually the opposite of true.”

“Wow Barry, I never knew that!” she smiled, then frowned a little. “How is your arm?” she asked carefully. She knew that Barry had been diagnosed with Hanahaki Disease over the summer, he was forced to leave the summer programme he had been looking forward to for almost two years.

“It's fine.” he insisted, shrugging it off.

“Let me see.” she insisted.

Barry sighed and hesitated for a moment, but then his hand moved to his sleeve and he pulled it up to his elbow.

Green vines encircled around his wrist. They were at one point around his fingers but he managed to push them down so they were around his wrist. Sadly, now they had spread the opposite way, tangling up his arm, disappearing up past his sleeve. Thorns biting deeply into the skin.

“Barr …” she looked at him sadly.

“It's fine.” he shrugged, finishing his breakfast.

“It's not fine, Barry. They're spreading really fast. They were only around your wrist a few weeks ago. Now they're up your arm.”

“On my torso too, but that's normal, Iris. It's going to keep spreading. First it spreads externally, it will wrap completely around my torso first, then it will spread and start flowering in my lungs. I only have a few options.”

“Dad never lets me come to the check ups … what are your options?” she turned her hand over in his and grasped it tightly.

“Well, hypothetically if I found a Soulmate it would manage it better than I am currently, slow the process and even reverse it-- which is almost impossible, not everyone has a soulmate and I'm probably one of the point five percent of people who don't. I can confess my feelings and hope they're returned, or I could get surgery.” he shrugged.

“Why don't you tell them?”

“Because I'm never going to put them in a position where they know if they don't love me I could die. That's really shitty.” he shrugged.

“How about surgery, Barr?” she suggested, honestly not understanding why he wouldn't consider that route.

“I would never do that. Ever.” he said seriously.

“Why not?”

“Because I would never be able to love like this again. It would take away a part of who I am, and I don't want that.”

Iris stood and hugged him tightly, her arms locked around him tightly.

“Oh Barr.” she sighed. “I wish I could help you.”

Barry sighed and rubbed her back gently.

“I'll be okay.”

“You keep saying that like I'll just believe you.”

Joe sauntered down the stairs and headed into the kitchen.

“You kids better get going or you'll be late.” he warned.

Iris stood and grabbed her bag, waiting for Barry. When they were both ready they started to walk to school.

“If I stop making a big deal, will you promise to be honest when I ask you how you’re doing?”

“Okay.” he agreed reluctantly.

“Promise?” she pressed.

“I promise, Iris.” he threw an arm around her shoulders. "I'll be fine.” if he was being honest, his biggest concern was how he was going to hide the iris petals he had started to cough up a few days ago.


	2. Chapter 2

**Notes for the Chapter:**

> I did a part two, oops? ¯\\_(ツ)_/¯

**Central City 2007**

The morning trudged by slowly as Barry finished packing up one of his college-bound moving boxes. He lifted it up onto the stack of boxes in his room which were about as tall as Iris.

“You almost ready, Barr?” asked Joe.

Barry glanced up to see him in the doorway. 

“Almost yeah, I just need …” his eyes searched the room until they fell on his desk, grabbing the photo of him and Iris off of it he placed it in the final box. 

Barry wondered where Iris was, he wasn’t quite sure why he hadn't seen her that day. When Joe and Barry finished loading the boxes into the car she finally appeared. 

“Wait for me!” she announced, sliding into the back seat. “Barry sit with me.”

Barry slid into the back with her and she took his hand. They just sat in the back together, talking for the entire hour long drive about anything and everything. Childhood memories, inside jokes, Iris’s newest celebrity crush was even brought up a few times.

“We're here.” said Joe after a bit.

 

The brought his boxes to his dorm and Iris insisted on helping him unpack and get settled in. When they reached the last box she opened it and pulled out the photo of them which laid carefully on top of everything in the box.

“You brought this?” she stared at the photo. It had an aged yellow tint and the two were probably ten or eleven when it was taken. She couldn't remember if it was before or after his mother’s death.

“I … yeah … sorry. Did you want it?” he asked awkwardly.

Joe stepped out of the room without saying anything. He hoped maybe they would talk things out. So he gave them privacy.

“No,” she shook her head, a small smile playing on her lips. “it belongs here.” she sat the frame carefully on his desk.

They stared at each other for a moment before Iris stepped forward and wrapped her arms around Barry tightly.

Barry leaned down and returned the hug. It didn't take too much time before they were both crying, holding onto each other tightly.

“I'm going to miss waking up without you in the house.”

“I'm going to miss you.” he kissed her cheek.

Soon she and Joe left, and something changed. When she was gone he felt a discomfort in his chest as the vines wrapped tightly around his lower chest and abdomen, thorns biting deeper into flesh than before. He was wrong, Iris was one of his Soulmates. How did he not notice that the thorns were spreading slowly until now? He figured that with how casual their contact was around the house, he never suspected anything. Afterall, Iris had been holding his hand, playing with his hair, and kissing his face for years before he contracted Hanihaki Disease, so why would he notice?

 

After a lot of consideration, Barry decided to tell Iris that she was his soulmate. He wouldn't tell her how he felt yet, or maybe even ever, but he had to tell her about this.

He headed in the front door at the start of summer break and called through the house. 

“Iris?--” he coughed hard and he felt something stuck to the back of his tongue. he slid a finger back and pulled it out. A single purple petal with a yellow marking. It was getting worse. “Iris?” he called again. He heard a coughing sound from upstairs and followed it. Iris sat at her vanity, coughing into her hand. Petals littering the floor around her feet.

“Iris? Are you okay.” he stepped forward and the soft petals squished into the cheap green carpet that covered the floors in her room. He looked down and saw yellow petals, bulbus with pinched ends, that  Barry assumed belonged to Sunflowers.

“Why didn't you tell me you had it too?” asked Barry, concern rising in his tone.

“Because, if I just had a cold you would run home to me.” she smiled a little.

“Of course I would have! You’re--” his voice choked up slightly. “My best friend,” he finished. “Do you trust me?”

“I trust you, Barr.” she looked confused, but nodded seriously.

Barry carefully peeled off his shirt, being careful of the vines weaving in and out of his skin, violently constricting his chest. Subsequently, he took her hand in his and placed her palm flat against the skin of his chest, which was a little hard with all the vines, but he managed.

After a few minutes, Iris felt the vines around her own chest slowly start to recede, fading into her skin and her breathing became easier. She stared at him in disbelief.

“What just happened?” asked Iris after taking a deep, clear breath for the first time in days.

“Our immune systems respond to each other’s. Cycles of physical touch with someone with a similar structure can help combat the symptoms of Hanahaki,.”

“Oh right. You did say that once. How did you know we were soulmates?” she asked.

“When you left after I moved into my dorm the Hanahaki vines spread quickly and I had an episode very similar to an asthma attack.”

“I'm sorry, Barr.” she frowned, taking his hand.

“Don't apologise for science being stupid.” he sighed and crossed his arms. “It's not our fault we’re so lovesick.” he laughed. 

She reached forward and took his hand, placing it against the small bit of skin left exposed around the swoop neck of her shirt.

He breathed deeply and when the vines were manageable he shyly pulled his hand away.

“Are you okay?”

“I think I'm going to be just fine.” she smiled a little and kissed his cheek. “How about you? Are you feeling okay?”

“I'm feeling a lot better,” he nodded. “Don't suppose you'll tell me who the sunflowers are for?”

“I'll tell you mine if you tell me yours,” there was a slight smirk on her lips. Of course she was messing with him now.

“I'm not ready.”

“Okay, Barr.” 

**Central City 2010**

 

Iris headed into Barry’s apartment on a Friday night. The city was buzzing and she had considered going out to a club, but she was feeling under the weather, so she went to see him instead. The two were unable to meet up and  _ sync up  _ as they'd taken to calling it for almost three months. So neither of them was doing great.

“Barr?” she called and Barry appeared in the front room. His apartment was small. Two main rooms, the front where the kitchen and living room lived in harmony, a door off to bed broom and a door to a bathroom.

“Hey,” smiled Barry, coming out of the bedroom. 

“Barry you look like shit!” she informed him, taking in his usually tall and sunny form.

He was hunched over slightly, his breathing laboured. He looked tired, and stopped to lean on the sofa. His face was pale and his eyes sunken.

Iris moved to meet him, taking his hand firmly in hers. “I'm staying tonight.” one hand came up to touch his cheek and he leaned into her touch. After what felt like a lifetime, his breathing slowly returned to normal. “That took longer than before.”

“Yes. It's worse now.” he admitted.

“Okay, I'm staying. Want to go with Tracy and I tomorrow? We are going to talk to her florist for the wedding.”

“Wedding?”

“Yes … her wedding. You're supposed to be my plus one? It's in, like, a month, tell me you got a suit.” she sounded frustrated.

“Sorry, I forgot. I have a suit don't worry. Joe made me buy one when I got my job in the crime lab.” he rolled his eyes.

“Good.”

 

The next morning they were running a bit late (thanks to Barry, naturally) but they arrived at the florist shop.

“Thanks for coming Iris-- hi Barry.” Tracy sounded surprised to see Barry. 

“Hey Tracy.” he smiled. “I hope you don't mind me tagging along.”

“Not at all … do you know anything about flowers?”

“Flowers--” Barry started a very scientific info dump about flowers before Iris stopped him.

“Good, we have two types of experts in hand,” Tracy laughed softly.

Iris approached one of the tables that hard a vase full of large, yellow flowers.

“Oh, I  _ love _ Sunflowers!” Iris picked up one of the large flowers. “They remind me of you, Barry.” she smiled.

“T-they remind-- they remind you of me?” he stumbled over his words. “Why do they? Er why do they remind you of me?”

“Um, they're the Barry Allen of flowers,” Iris’s tone implied that it was obvious. 

“I completely agree!” Tracy laughed.

Barry swallowed thickly. 

“What's the matter with you? It's a compliment I swear.” Iris nudged his arm. 

“Nothing.” he rubbed the back of his neck awkwardly.  _ Don't get your hopes up. _ He scolded himself internally.

Iris helped Tracy pick out her flowers, Barry was little help, but he knew he would be going into it. 

“Do you guys want to grab lunch with Lyra and me?” she asked curiously. 

“You know, we actually have a thing … Barry has some unexplainable case things to finish up but we’ll see you two at the rehearsal dinner.” Iris smiled at her friend and soon she and Barry headed out. 

 

When they returned to Barry’s apartment, she cornered him. Quite literally. Despite her small stature, he didn't move, though he could have easily pushed past her.

“Okay, you're being weird.” she accused. " _Talk_."

“I'm not being weird-- How am I being weird? You're being weird,” he took a step back instinctively, but his back met the wall.

“Barry Allen, I know you like the back of my hand. Tell me what's going on.” 

“The Sunflowers.”

“Did I hurt your man-pride or something? It's just because you're bright and sunny. It's what I love about you.”

Barry just looked at her and they sat in silence for a second. Barry met her eyes and wrung his hands together anxiously.

“When I came home from college a few years ago,” he paused. “you were coughing up Sunflower petals.”

“Barry … do we have to do this now? Look I just,” she sighed. “I don't want things to change between us, so really don't worry about it.” she reached out for his hand.

“I need to know if they're for me or not.” he argued, but let her take his hand.

“Barry--”

“It's a yes or no question, Iris.” 

“Yeah, and if I answer it things are going to be weird.”

"Iris. Please.”

“Yes, Barry. Okay? They're for you.”

Barry stared at her for a second and a laugh started to rumble in his throat.

“I don't see why that's funny.” she crossed her arms, dropping hid hand. 

“Iris, we are a mess,” he put his hands on her shoulders. “Mine have always been irises, mine are for you.”

“We  _ are _ a mess,” Iris agreed and wrapped her arms around him in a tight hug. “Why didn't you say anything to me?”

“I was afraid of losing you, and of course the other reasons I gave you. Why did you never say anything?” 

“I think the same…”

“Let's go on a real date.” said Barry, without thinking the words came out in word vomit.

“Nah, let's go on a fake date instead!” she teased. 

“Well, we've been going on dates that weren't really dates for years.” 

“You are right.”


End file.
